Combining high power ultrasound and electrochemical analysis functions and properties has most often previously been achieved by configuring a high power acoustic resonator and separate electrode system in a face-on geometry. In such an arrangement, the spacing between the electrode and acoustic resonator can be varied to vary the effect of the separated acoustic and electrode systems. However, it should be noted, that the spacing between the acoustic resonator and the electrode system in the face-on geometry will result in a decrease in the electrode cleaning capabilities of the acoustic resonator and the mass transfer rate associated with the electrode when operated contemporaneously with the acoustic resonator. Furthermore, investigations with regard to performance of such face-on configurations identified the existence of wear and erosion issues associated with the systems
In another arrangement configured to provide for combined ultrasound and electrochemical analysis functions and properties, an acoustic horn of a high power acoustic resonator has itself been used as an electrode. In these configurations, the acoustic horn itself is used as the working electrode in an electrochemical circuit. Reisse et al. in an article entitled “SONOELECTROCHEMISTRY IN AQUEOUS ELECTROLYTE: A NEW TYPE OF SONOELECTROREACTOR,” Electrochim. Acta, 39, 37-39 (1994), disclose using a titanium ultrasonic horn as a working electrode to provide for depositing copper from a solution of copper sulphate in the presence of high power ultrasound at a frequency of 20 kHz. Durant et al. describe using a titanium horn as the working electrode to study the effects of high power ultrasound on the electrochemical reduction of benzaldehyde and benzoquinone. (Durant, A., François, H., Reisse, J. and Kirsch-de Mesmaeker, A., “SONOELECTROCHEMISTRY: THE EFFECTS OF ULTRASOUND ON ORGANIC ELECTROCHEMICAL REDUCTION,” Electrochim. Acta, 41, 277-284 (1996).
Other arrangements provide for attaching the electrode to an acoustic horn. Such an arrangement may be termed a sonotrode and such a device is available commercially from Windsor Scientific. The Windsor Scientific sonotrode consists of a glassy carbon disk electrode set in the end of a quartz rod, wherein the quartz rod is screwed into the end of an ultrasonic horn. Although the sonotrode is a combined system with the acoustic resonator and electrode combined, the electrode is still disposed distally from the acoustic horn; so as with the face-on geometry, the separation will result in a decrease in the electrode cleaning capabilities of the acoustic resonator and the mass transfer rate associated with the electrode when operated contemporaneously with the acoustic resonator. Further, the Windsor Scientific sonotrode does not provide a rugged and wear/erosion resistant design and may not be capable of operating at high acoustic powers and/or may experience degradation of the glassy carbon disk electrode under acoustic functions. In another sonotrode-type device, Simm et al. “SONICALLY ASSISTED ELECTROANALYTICAL DETECTION OF ULTRATRACE ARSENIC,” Anal. Chem., 76, 5051-5055 (2004), an electrode may be attached to a small permanent magnet that may be made to vibrate by passing current through an adjacent electric coil.
In a further acoustic resonator and electrode arrangement, modifying the idea of using the acoustic horn as the electrode, a platinum electrode is disclosed that is bonded into a hole drilled in the titanium tip of an acoustic horn using an adhesive. (Compton et al., “ELECTRODE PROCESSES AT THE SURFACE OF SONOTRODES,” Electrochim. Acta, 41, 315-320 (1996)). In such an arrangement, as with arrangements wherein the acoustic horn acts as an electrode, the distance between the electrode and the acoustic horn does not become an issue. In the electro-acoustic system disclosed by Compton, electrical connections to the platinum electrode are provided by wire connections passing through the side of the acoustic horn to the platinum electrode. While the reference provides a sonotrode that effectively addresses issues regarding separation of the acoustic resonator and the electrode it does not address using acoustic energy to clean the electrode or provide for effectively configuring the acoustic resonator and electrode system for combined operation. Furthermore, the reference does not disclose a sonotrode that may be suited for remote operation, operation in harsh environments—including high temperatures or pressures—or that can be effectively used repeatedly at high acoustic energy levels.